CN1235044C

CN1235044C - Film optical addressing electric potential sensor used for detecting Hg2+ and preparation method thereof

Info

Publication number: CN1235044C
Application number: CN 200310109501
Authority: CN
Inventors: 王平; 门洪; 李毅; 许祝安
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2003-12-14
Filing date: 2003-12-14
Publication date: 2006-01-04
Anticipated expiration: 2023-12-14
Also published as: CN1547004A

Abstract

The present invention discloses a light addressing potential sensor for detecting Hg2+ films and a preparation method thereof. The sensor is based on a light addressing potential sensor (LAPS), and a layer of sensitive film is prepared on a surface of the sensor with a pulsed laser deposition (PLD) technology. Firstly, sensitive material is synthesized as a pulsed laser deposition target; secondly, a fixed metal layer through the magnetron sputtering technology is prepared on LAPS; finally, a film is prepared on the basis of the pulsed laser deposition technology and equipment. The film sensor sensitive to the Hg2+ in the liquid can detect the content of Hg2+. The present invention can be used for qualitative and quantitative detection on Hg2+ in the fields of water, biomedicine (such as blood and body fluid), industrial sewage, traditional Chinese drugs, vegetable, fruits, tea leaves, etc.

Description

Be used to detect Hg 2+Film light address electric potential sensor and preparation method thereof

Technical field

The present invention relates to a kind of Hg that is used to detect ²⁺Film light address electric potential sensor and preparation method thereof.

Background technology

Heavy metal ion is (as Zn2+, Pb ²⁺, Cd ²⁺, Cu ²⁺, Cr ⁶⁺, Mn ⁵⁺, As ³⁺, Fe ³⁺, Hg ²⁺) can produce harmful even fatal influence to human body, so the detection by quantitative of heavy metal has very important meaning at aspects such as medicine, food, clinical and environmental monitorings.Present detection method mainly contains atomic absorption spectrophotometry and mass spectroscopy etc., but adopt the equipment of these methods huge, and expensive, need complicated pretreatment, measuring period is long and need skilled operating personnel, and this brings many inconveniences in actual applications.

Summary of the invention

The object of the present invention is to provide a kind of Hg that is used to detect ²⁺Film light address electric potential sensor and preparation method thereof, can be to Hg ²⁺Carry out qualitative and detection by quantitative.

In order to achieve the above object, the technical solution used in the present invention is as follows:

1, structure of the present invention:

Select for use p type or n type Si sheet to do substrate, substrate from down and on SiO is arranged successively ₂Layer, metal level, to Hg ²⁺Responsive film.Metal level is that lower floor is Cr, and the upper strata is Au; Or lower floor is Ti, and the middle level is Pt, upper strata Au; Or lower floor is Ti, and the upper strata is Pt.

2, preparation method of the present invention:

(1) preparation of LAPS

Select p type or n type＜100 for use〉monocrystalline silicon piece is as the substrate of LAPS.Silicon chip is put into high temperature furnace and is carried out thermal oxide after polished and cleaned, and making the silicon chip front layer thickness of growing in dry oxygen is the SiO of 30nm ₂Film, with ion etching method the oxide layer at the silicon chip back side is removed, starch the Ohmic contact of making an annular with silver then and draw lead, except annular position stays for the illumination, remainder is all used epoxy sealing, promptly makes LAPS, adopt magnetron sputtering technique at LAPS plating metal on surface layer, guarantee that film and LAPS combine closely, wherein metal level has three kinds as selecting: being respectively lower floor is Cr, and the upper strata is Au; Or lower floor is Ti, and the middle level is Pt, upper strata Au; Or lower floor is Ti, and the upper strata is Pt;

(2) preparation of sensitive material

Select high-purity compound AgI: Ag for use ₂S: HgI mol ratio 55～60: 25～30: 12～16, fully behind the mixed grinding, under 10Mpa pressure, make little rectangular parallelepiped, be put in the quartzy bottle, be under the dry condition of nitrogen gas, be heated to 400 ℃, kept 3 hours; Naturally annealing then, broken little rectangular parallelepiped grinding again again, making diameter is 3cm, thickness is the circle sheet of 2mm; Be placed in the vitreosil bottle, be heated to 400 ℃, kept 3 hours, the preparation of sensitive material has promptly been finished in annealing naturally, and the sensitive material after synthesizing is the target of pulsed laser deposition technique;

(3) preparation of film

Adopt pulsed laser deposition technique, prepare sensitive thin film on LAPS, promptly prepared sensitive material is as the target of pulsed laser deposition in the optional step (2), and pulsed laser deposition equipment is made up of laser generator and vacuum chamber; In order to guarantee combining closely of film and metal level, substrate is warmed up to 100 ℃, and preheating 20 minutes finishes the back in deposition and kept 10 minutes, and cooling naturally in vacuum chamber has then so just formed Hg ²⁺Responsive film.

The advantage that the present invention has is: detection means is little, and sample solution is few, measures fast, and is easy to use, measures accurately, almost can interferometry without any metallic ion.This thin film sensor can be to Hg in fields such as rivers,lakes and seas, biomedical sector such as blood, body fluid etc., industrial waste water, Chinese medicine, vegetables, fruit, tealeaves ²⁺Carry out qualitative and detection by quantitative.

Description of drawings

Below in conjunction with drawings and Examples this outbreak is further specified.

Fig. 1 is the basic block diagram of first kind of sensor of the present invention;

Fig. 2 is the basic block diagram of second kind of sensor of the present invention;

Fig. 3 is the basic block diagram of the third sensor of the present invention;

Fig. 4 is that pulsed laser deposition technique prepares the thin-film process schematic diagram;

Fig. 5 is that pH is to Hg ²⁺Select the influence of thin film sensor;

Fig. 6 is a Mercury Ion Selective Thin Film Sensor I-V curve;

Fig. 7 is the typical curve of Mercury Ion Selective Thin Film Sensor.

Embodiment

The structure of sensor

Select for use p type or n type Si sheet to do substrate, substrate from down and on SiO is arranged successively ₂Layer, metal level, to Hg ²⁺Responsive film.Said metal level is that lower floor is Cr, and the upper strata is Au, as shown in Figure 1; Or lower floor is Ti, and the middle level is Pt, upper strata Au, as shown in Figure 2; Or lower floor is Ti, and the upper strata is Pt, as shown in Figure 3.

The preparation of sensor

(1) preparation of LAPS

Select p type or n type＜100 for use〉monocrystalline silicon piece is as the substrate of LAPS.Silicon chip is put into high temperature furnace and is carried out thermal oxide after polished and cleaned, makes the silicon chip front layer thickness of growing in dry oxygen be about the SiO of 30nm ₂Film, with ion etching method the oxide layer at the silicon chip back side is removed, starch the Ohmic contact of making an annular with silver then and draw lead, except annular position stays for the illumination, remainder is all used epoxy sealing, promptly makes LAPS, adopt magnetron sputtering technique at LAPS plating metal on surface layer, guarantee that film and LAPS combine closely, wherein metal level has three kinds as selecting: being respectively lower floor is Cr, and the upper strata is Au; Or lower floor is Ti, and the middle level is Pt, upper strata Au; Or lower floor is Ti, and the upper strata is Pt; Excitation source adopts the front or the back side all can;

(2) preparation of sensitive material

Select high-purity compound AgI: Ag for use ₂S: HgI mol ratio 57.1: 28.6: 14.3, fully behind the mixed grinding, under 10Mpa pressure, make little rectangular parallelepiped, be put in the quartzy bottle, under the condition of nitrogen gas of drying, be heated to 400 ℃, kept 3 hours; Naturally annealing then, broken little rectangular parallelepiped grinding again again, making diameter is 3cm, thickness is the circle sheet of 2mm; Be placed in the vitreosil bottle, be heated to 400 ℃, kept 3 hours, annealing has promptly formed the required target of pulsed laser deposition naturally;

(3) preparation of film

Adopt pulsed laser deposition technique, prepare sensitive thin film on LAPS, pulsed laser deposition equipment mainly is made up of laser generator and vacuum chamber; Figure 4 shows that pulsed laser deposition technique prepares the film schematic diagram, the laser beam scioptics shine on the sensitive material target material surface after focusing on, and the reflection back forms plasma slab at target material surface, and the sensitive material that excites is evaporated in the substrate, forms sensitive thin film.The preparation process parameter is as shown in table 1.In order to guarantee combining closely of film and metal level, substrate is warmed up to 100 ℃, and preheating 20 minutes finishes the back in deposition and kept 10 minutes, and cooling naturally in vacuum chamber has then so just formed Hg ²⁺Responsive film.

Table 1 pulsed laser deposition technique prepares the thin-film process parameter

The deposition process parameter	Experiment value
The deposition process parameter	Experiment value	Energy density wavelength pulse width repetition rate sedimentation time pressure base reservoir temperature target material	0.2J/cm ² 248nm 30ns 1.3Hz 40min 0.2mbarN ₂ 373K Hg-Ag-I-S

Principle of sensors

The change of semiconductor Dc bias can cause the variation of inner photogenerated current, and in the constant LAPS of fixed-bias transistor circuit, film is to the Hg in the electrolyte solution ²⁺Selectivity be the determinative that electric current causes variation in the loop, different concentration can cause the change of electric current, changes by the electric current of measuring in the external circuit, just can reflect the Hg in the solution ²⁺Concentration.

Excitation source adopts laser diode, can front or back side illuminaton; Contrast electrode is selected platinum electrode or Ag/AgCl for use; Ohmic contact is drawn lead and is connect direct supply, and direct supply has been the effect of bias voltage; Measure solution and can cause the variation of sensitive membrane current potential, thereby cause that the electric current in the circuit loop changes, just can measure contained Hg in the solution by the photocurrent variations that measures ²⁺Concentration.

The characteristic of sensor

(1) influence of pH value

PH can influence the electrical characteristics of thin film sensor, so tested the suitable usable range of the pH value of this sensor.Fixed concentration 10 ^-3With 10 ^-5Mol/L is constant, disposes different pH Hg ²⁺Solution, test result is seen Fig. 5.In 0～2 scope, pH does not almost have too much influence to thin film sensor, but when pH＞2, the voltage responsive meeting significantly descends.

(2) I-V curve

Thin film sensor is to Hg ²⁺The I-V scanning curve as shown in Figure 6, substrate is a p type silicon, horizontal ordinate is a bias voltage, ordinate is the response current after the normalized.Hg ²⁺Concentration range 10 ^-1～10 ^-5Mol/L.This result shows that thin film sensor is to Hg ²⁺Has higher selectivity.

(3) family curve of sensor and characterisitic parameter thereof

Thin film sensor is to Hg ²⁺Optionally typical curve as shown in Figure 7.Be limited to 3 * l0 under detecting ^-6Mol/L.The response time of sensor omits hurry up when concentration is high relatively less than 2min.And when measuring high concentration Hg ²⁺Behind the solution, when measuring low concentration again, do not find significant concentration hesitation phenomenon.This thin film sensor is to nearly all metallic ion such as Fe ³⁺, Na ⁺, K ⁺, Ca ²⁺, Cd ²⁺, Zn ²⁺, pb ²⁺, Cu ²⁺, Cr ³⁺Deng all insensitive, this also is characteristics of this sensing.

Claims

1, a kind ofly is used to detect Hg ²⁺The film light address electric potential sensor, select for use p type or n type Si sheet to do substrate, substrate from down and on SiO is arranged successively ₂Layer, metal level, to Hg ²⁺Responsive film, it is characterized in that: described metal level is that lower floor is Cr, and the upper strata is Au; Or lower floor is Ti, and the middle level is Pt, upper strata Au; Or the upper strata is Ti, and lower floor is Pt.

2, a kind ofly be used to detect Hg ²⁺The preparation method of film light address electric potential sensor, it is characterized in that:

(1) preparation of Light Addressable Potentiometric Sensor

Select p type or n type＜100 for use〉monocrystalline silicon piece is as the substrate of Light Addressable Potentiometric Sensor, and silicon chip is put into high temperature furnace and is carried out thermal oxide after polished and cleaned, and making the silicon chip front layer thickness of growing in dry oxygen is the SiO of 30nm ₂Film, with ion etching method the oxide layer at the silicon chip back side is removed, starch the Ohmic contact of making an annular with silver then and draw lead, except annular position stays for the illumination, remainder is all used epoxy sealing, promptly makes Light Addressable Potentiometric Sensor, adopt magnetron sputtering technique at Light Addressable Potentiometric Sensor plating metal on surface layer, assurance film and Light Addressable Potentiometric Sensor are combined closely, and wherein metal level has three kinds as selecting: being respectively lower floor is Cr, and the upper strata is Au; Or lower floor is Ti, and the middle level is Pt, upper strata Au; Or lower floor is Ti, and the upper strata is Pt;

(2) preparation of sensitive material

Select high-purity compound AgI: Ag for use ₂S: HgI mol ratio 55～60: 25～30: 12～16, fully behind the mixed grinding, under 10Mpa pressure, make little rectangular parallelepiped, be put in the quartzy bottle, under the condition of nitrogen gas of drying, be heated to 400 ℃, kept 3 hours; Naturally annealing then, broken little rectangular parallelepiped grinding again again, making diameter is 3cm, thickness is the circle sheet of 2mm; Be placed in the vitreosil bottle, be heated to 400 ℃, kept 3 hours, the preparation of sensitive material has promptly been finished in annealing naturally, and the sensitive material after synthesizing is the required target of pulsed laser deposition;

(3) preparation of film

Adopt pulsed laser deposition technique to prepare sensitive thin film on Light Addressable Potentiometric Sensor, promptly prepared sensitive material adopts pulsed laser deposition technique as the target of pulsed laser deposition in the optional step (2), and preparation is to Hg on Light Addressable Potentiometric Sensor ²⁺Responsive film, pulsed laser deposition equipment is made up of laser generator and vacuum chamber; In order to guarantee combining closely of film and metal level, substrate is warmed up to 100 ℃, and preheating 20 minutes finishes the back in deposition and kept 10 minutes, and cooling naturally in vacuum chamber has then so just formed Hg ²⁺Responsive film.